


Black Water

by FictionalQuacker



Category: Harry Potter - J. K. Rowling, Harry potter Hogwarts mystery, Hogwarts Mystery
Genre: Adventure, F/F, Friendship, Gen, Hogwarts, Hogwarts Mystery - Freeform, Magic, Potions, Potions Accident, The Black Lake, Transformation, mermaid
Language: English
Status: In-Progress
Published: 2018-08-12
Updated: 2018-09-19
Packaged: 2019-06-26 06:48:48
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 12,323
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15657966
Author URL: https://archiveofourown.org/users/FictionalQuacker/pseuds/FictionalQuacker
Summary: Powerful potions are not to be trifled with but it takes more than a little danger to stop an ambitious witch like Merula Snyde from risking her life to reach her goals. The hunt for the cursed vaults has lead the aspiring curse-breakers to try and search the Black Lake for an underwater vault, but working together seems too difficult when you don't exactly get a long even under normal circumstances. Instead of sticking to the plan Merula tries to do it all on her own, not realizing her own limits.Struggling against feelings of lonliness and isolation, Merula is torn between her need for love and friendship and her fear of failing should she try to have it. Despite her desire for connection there is too much distance between her and the people who would help her. To cross that distance she must change, as difficult that is for anyone, she must do it... and change she will.





	1. Syreni potion

It was a chilly evening, the cold temperature of the air contradicting the warm colors from the setting sun painting the castle a golden orange. The heavy clouds on the sky seemed orange too, however as soon as the sun disappeared behind the horizon they would leave Hogwarts shrouded in black night with not even the moon to brighten up the school grounds. As it was slowly getting darker, a small figure was jogging up the stairs to the owlery. Her brown hair was unruly to the point of being almost spiky and a red stripe in her bangs stood on edge as if it had been styled to stand alone from the rest of the hair. Her black and green robes were wrinkled, but the high quality fabric flowed with her every movement. She was wearing a Slytherin tie around her neck that was so close to undone it seemed dangerously close to abandoning her as she quickly made her way into the room full of owls.

Many of the birds made angry noises when she entered so violently, but one of them just gently cooed in happy surprise and flew to perch on her shoulder. The bird rubbed its' beak against the girls' cheek and she gave it a quick pat on the head. She dug her hand into the big pocket on the inside of her robes and fished out an envelope. Nothing was written on it, but for once it did not matter. In fact, it was more likely to reach its’ destination with no address exposing where it was supposed to go. She fastened her letter to its' leg with a simple piece of grey string.

“Go off then, you know where to go.” She said to the bird, and gave it a treat from her pocket.

The bird swallowed the food in one swift movement and took off. Quickly yet silently it flew out of the tower. She watched the bird vanish into the distance and then watched the sky as the last few rays from the setting sun faded away and left her and the castle in the dark of night. She closed her hands into fists and told herself that this time her owl would come back with more than an empty stomach and even emptier claws. The prospects were not looking good, but at least she could hope for the best. She sighed and realised that it would not improve her situation to stay out much longer past curfew and risk yet another scolding from her head of house.

_Tsk, Snape can be such an… an ape! He’s not even that powerful a wizard and still has the nerve to yell at me for stupid things that aren’t even my fault._ She thought, still angry about the earful she had received for being caught lying to him the other day. It was a white lie, but he had not seemed to care much her intentions.

She went back down the stairs and made her way back towards the dungeons. Once back in the Slytherin common room she started to relax and undid what remained of her necktie before even walking into her dorm. Ismelda, currently her favorite person in her year besides herself, was sitting on her bed perched over an old book with black leather covers in the light from her wand. Her long black hair was tied up in a bun on the top of her head so you would not guess how dirty it was, but Merula knew her friend and how she only washed once every sunday… Today was thursday. She was wearing her knitted Slytherin scarf over dark green pyjamas with silver embroidery on the chest and cuffs, apparently there was no such thing as a situation that did not call for their house colors to be on full display to the pale Murk girl. To her credit she did do a wonderful job at blending right in with the murky colors and gothic style of the Slytherin dorms and common room.

The other inhabitants of their dorm seemed to be sleeping, one of them snoring from underneath the covers.

“You’re pretty late, Merula. Did you send another letter?” Ismelda did not look up from her book, although you could tell she was no longer reading whatever was in it since her eyes had stopped moving across the page. Merula threw her robe and tie onto a chair and got to taking off her shoes.

“Yeah. I don’t think it will go through but even so…” she threw her shoes at the chair and one of them hit her robe, leaving a large print of dirt on the fabric. Ismelda straightened her back and closed the book. She looked Merula in the eyes, her black stare as blunt and brutally honest as her words.

“You haven’t had a single reply this whole year, why are you still sending more letters to them? It’s clearly futile.” She was right, obviously. That is exactly why it hurt Merula to hear it being said. Her fingers trembled as she buttoned her pyjamas.

“They’re my parents. I won’t give up on family, Ismelda.”

“Duh. But why aren’t you changing up your strategy? Your family belongs to the Dark Lord’s people! It would be easy to find contacts, I bet the Malfoys could pull some strings to-...”

“Yeah well the bloody Death Eaters weren’t too protective of my mum and dad when they got caught by the ministry were they? They let them get locked up in that horrible place without even putting up a fight for them!” Merula snapped at Ismelda, who glared back at her with a wrinkle between her eyebrows. Merula sighed and backed down a bit.

“...whatever. What I mean is I just don’t know if I could ask the people my parents knew back then to smuggle letters in and out of Azkaban. Even if they were loyal to… to the Dark Lord that doesn’t mean they’ll risk their security to help me out now. The only reason we’ve been able to communicate before is because of our old servant landing a job connected to the prison.” Talking about it made her head ache. Merula had been over this in her mind a hundred times by now, plotting out every course of action she could think of. The cunning she usually could rely on got her nowhere, and it was beyond frustrating. As much as she hated it she was forced to wait for something to happen to change the situation for her before she could act.

“Well if you do want something you should really ask your friends first. Barnaby may have run off with a group of blood-traitors but you still got people holding your back.” Ismelda said with a somewhat softer voice than her usual tone. She made a nonchalant motion with her wand and put out the light.

Merula crept under the heavy covers on her own bed and saw Ismelda do the same in hers before she closed the curtains.

“...you sound almost like a Hufflepuff when you say soft crap like that.” Merula muttered and heard Ismelda snicker.

That night Merula slept in short intervals without dreaming, and when the other girls woke her up her body felt heavy as if her limbs were made mainly of led instead of flesh and bones like a normal human. She forced herself out of bed and watched Ismelda doing her greasy hair in front of her mirror. She had already drawn around her eyes with black pencil that made her look quite menacing. Yawning, Merula picked up her own mirror to inspect the state of her face. Having had sleeping problems the entirety of her short life had left the skin around her eyes dark and sunken, which was especially obvious on somebody as pale as Merula. To cover it up she brushed on a layer of _Madam Merci’s Magic Concealer Powder_ all over her face, followed by a smokey eyeshadow on her eyelids. The concealer powder lit up for a second after she applied it, but then it seemed to merge with her skin and left it looking beige and flawless. Satisfied with the results, Merula left her hair as it was and turned to Ismelda.

“Honestly Ismelda, bathing is not optional unless you feel like moving in with the other beasts in the forbidden forest.” She could see Ismelda’s reflection rolling her eyes. Merula’s head began to hurt and she still felt heavy, wanting nothing more than a few more hours in bed. She contemplated pretending to be sick to try and get out of potions class so she could go back to sleep. After some convincing herself it was not worth losing Slytherin house points over tiredness she joined the drowsy crowd going to the Great Hall for breakfast.

Merula’s stomach grumbled unhappily as they went but the thought of toast and tea kept her happy on the way. While walking up the stairs leading them out of the dungeon one of her classmates, Liz Tuttle, tripped and grabbed Merula’s arm to steady herself. She was a geeky but very pretty girl with big hair, dark lips and soft brown skin. The green Slytherin robes were very flattering on her, too. Merula suddenly noticed she had a certain glimmer to her eyes underneath her round glasses. They did share a dorm room but they were not as close as her and Ismelda. Liz had been polite with her ever since their first year, but for some reason Merula always felt a little bit embarrassed and flustered around her, so the sudden touch made her blush a deep red. Gasping, Liz quickly apologised and let go of Merula’s arm.

“Oh sorry! Didn’t mean to grab you like that with no warning.”

“I-it’s fine. Don’t make a fuss about it.” Merula looked anywhere but at Liz, hoping she had not noticed the red on her cheeks. She felt a desperate need to reach the Great Hall already.

Between her and the sweet comfort of a generously loaded breakfast table however, stood a familiar figure. Leaned against the doorway to the Great Hall was her least favorite classmate and rival for the cursed vaults. They had a proper name but everyone called them M.C. for short whenever they did not just make a reference to their far more famous sibling, Jacob. Merula made a deep disgruntled groan as M.C. waved at her, clearly wanting something from her.

“Can’t I at least have breakfast before you start your daily routine of being annoying?” Merula greeted M.C. as they strolled over, blocking her way into the hall. The smell of tea and bacon coming through the doorway made her stomach growl loudly, and she quickly punched herself in the gut to make it quiet. M.C. just smiled that stupid warm grin they always had.

“Sorry to hold you up when you’re hungry but I need to talk to you and I’d rather not wait.” M.C. said with a glint in their eye. Merula raised her eyebrows at them.

“Is it about the cursed vaults? That’s the only thing involving you interesting enough to be pre-breakfast business.” She responded, and M.C. nodded.

“We suspect there is one in the Black Lake. Penny is working on a potion to let us go down there but she needs someone to assist her in making it.” That peaked her interest, indeed.

“Assist her? And you’re asking me? To help you lot?” Merula asked, wondering why on earth her rival would ask her of all people. Then again M.C. did many things that made no sense. Probably a side effect of being who they are as a person... and a massive fool. She thought, feeling quite smug about it. M.C. tilted their head and gestured with their hand as if to signal they knew it sounded silly but still needed to ask.

“Yeah. You're the best at potions we know..." they stopped for a second to clear their throat "..and Penny said we can’t afford to make any mistakes on this potion so we need your help with this.” Merula thought about it. She was of course great at potions just like everything else, this was no doubt the truth... but hearing it from M.C. of all people made it somewhat suspicious.

“But why should I help you and your group of losers?” M.C. hesitated, as if taking time to decide what to say next. “You’ll get to use the potion too, and get closer to the vault at the same time we do.” They finally said and Merula considered the offer carefully.

It was a good point, and she had been quite distracted by trying to contact her parents so she had not made much progress on her own plans to get the next vault. It would benefit her to join and possibly leech off the M.C. groups’ progress and even if their plan ended up failing she would not lose out to them. It seemed like a pretty solid win-win.

“In that case, it’s a deal. Tell Penny to send me an owl with the details.” Merula agreed and felt quite a lot more confident than she had in the dorms. Confident, but hungry. Her stomach let out another loud growl and she made her way towards the perfectly cooked food that had been left waiting for too long.

 

* * *

 

After breakfast the Slytherin fourth-years had a double potions class scheduled with Hufflepuff. Merula realized that perhaps there was no point to ask for Penny to send her an owl but she had not remembered they had class together so soon and sure enough, while she and Ismelda were waiting outside the classroom Penny came up to them.

Cheery and bright as always, Penny shot a big white smile at them and ignored Ismelda’s sour scowl.

“Hello Merula, Hello Ismelda.” Penny greeted them. She had the ability to charm people into liking her, so it made perfect sense she was the most popular person in their year and quite possibly in the whole school. Pretty, smart and very socially competent she had everything she needed to make most people want to get close to her. Merula eyed her suspiciously up and down, trying to determine just how much of her friendly behavior was sincere.

“Are you looking to get cursed? I’d gladly try one I practiced last night on you...” Ismelda threatened with a small grin. Merula had noticed she always spoke in a much lower, grimmer voice with people she did not like. Her normal tone was a lot less threatening and edgy.

“I know professor Snape favourites Slytherin but I still don’t think it would be very cunning to curse one of his students right outside his classroom.” Penny shot back in a sharp tone and Ismela’s grin faded. Merula rolled her eyes at both of them.

“You’re one to talk, you’re clearly the teacher’s pet even with Snape...” Merula stopped talking when she noticed Penny and Ismelda were suddenly looking past her at something behind her.

“Miss Snyde.” The dragging, distinct voice of their potions master hissed. Severus Snape was standing menacing right behind Merula, having appeared suddenly and without warning. Sweating down her neck, she slowly turned around to face her teacher. He was looking down on her with unrestrained disapproval on his face.

“P-professor.” She stammered, Snape usually did not punish the Slytherins unless it really could not be avoided but even so his sharp glare and tone was penetrating enough to make just about any fourteen year old nervous. He scowled at her.

“Speak more respectfully about your professors, and don’t make accusations of favouritism unless you hope to be… unfavoured yourself.” His words made it quite clear Merula was on thin ice with the professor, even if he was her head of house. Which of course was all the more reason to make sure she was as much on his good side as possible. She bent her head down apologetically and made her best attempt at looking very sorry.

“I’m so sorry, professor... sir. I didn’t mean it to sound like that, I was just jealous that Penny gets so much of your attention…” She glanced up at him to see his reaction. “You’re my favourite teacher so I want to be your favourite, too.” She quickly added. Snape raised an eyebrow at her.

“Well, teachers are not supposed to have any favourites so you better drop this nonsense... for your own good.” Snape cleared his throat and went to open the door to the classroom. “Class is starting! Mister Lee, stop sleeping on that bench and get to your station!”

Eight hours stuck in an underground classroom full of small fires, boiling liquids and the heavy scents from Snape’s large assortment of dried plants and animal parts was seldom a pleasant experience but at least the company was bearable. The Slytherins much preferred the Hufflepuff’s company at the more uncomfortable lessons. Say what you want about them but there was no denying them being the friendliest house and they certainly were helpful to have around once you befriended them. Merula had just accepted a swig of iced pumpkin juice from a Kind Hufflepuff boy who carried around an enchanted bottle that apparently served any liquid at the desired temperature for the holder when Penny came up to their table. Apologetically, she shrugged her shoulders.

“Could you please help me pick out my last ingredient? I can’t seem to make up my mind on which is the right one.” She said with a wink at Merula. Merula followed her to the shelves with ingredients where they could speak without the others at the table hearing them. After casting lumos, Penny pretended to be reading labels but whispered to Merula.

“We think we know where the next vault is, and it’s in the middle of the Black Lake.” She picked up a small jar and leaned slightly closer. “As in the very center. We’ll make a powerful syreni potion to get there.” She put the jar back and continued her fake browsing. Merula joined in and inspected a jar of pickled frog legs.

“Where are we brewing?” She whispered at Penny, who gently ran her finger across the side of a box of bezoars.

“Do you know where the old artifact room is?” Penny glanced at Merula, she had a surprisingly mischievous look on her face and her eyes shone in the light from her wand. It was impossible not to notice how pretty Penny was, but Merula refused to be distracted.

“I think I’ve passed it once or twice.” She responded softly.

“Good, we’ll make the potion in that room after today’s classes and then make our move from there.” Penny smiled and plucked a tall, skinny jar from the top shelf without even looking at it. She winked at Merula.

“Found it! Oh thank you so much, Merula! You were a great help!” Penny spoke loud enough for Snape to overhear the last part and he seemed to look less discontent when Merula looked over at him.

“Five points to Slytherin.” She heard him mutter when she passed him on the way back to her table. Delighted, she continued brewing her potion.

 

* * *

 

As it turns out, the potion Penny was making was far more complicated than Merula had expected. Even she, the best student at Hogwarts, had to concentrate fully on what she was doing to keep up with Penny in the many steps and precise measurements. It did not help the matter that they had to hide out in the artifact room. Cramped, and way too warm when there was a flame going, she and the others were constantly sweating even after they had tossed their robes in a pile by the door.

As she was carefully adjusting the flame under the cauldron while both Penny and M.C. watched her every movement Barnaby barged into the room wrestling a great yellow toad with blue feet in his arms. Merula brushed her hair back from her face to keep it from getting stuck against her sweaty forehead and shot Barnaby a bitter look. She had still not forgiven him for leaving her gang to be friends with M.C. and their pack, and she felt as though she would never forget it. Loyalty was a core component of what she expected of her friends, and it was at the center of their house morals too.

“Good job Barnaby! That looks exactly like the toad in the instructions!” Penny smiled over the cauldron at the tall, beefy boy trying to calm the angry creature down. One of its’ legs got loose and kicked him straight in the jaw but the tough boy remained unfazed and simply rolled over and pinned the entire animal to the ground. He spat out a speck of blood before talking.

“There there, I understand you’re upset but you’ll be back in your pond in no time. I promise! Do you want some more meat maybe?” The sight of the toughest nut in their year trying to reason with a great angry toad was enough to make Merula stand up and laugh loudly at her former friend. M.C. put on some dirty leather gloves that looked like they came straight from a herbology lesson, and somehow managed to get a glass vial into the toads’ mouth and a thick, milky substance filled it. Penny cheered as M.C. handed the vial to her.

“Guess I’ll just… take this guy back then? If you’re done with him?” Barnaby grunted from on top of the toad who had stopped moving and now seemed to secrete a slippery slime.

“Yes, thank you so much Barnaby. This is perfect for the final steps!” Penny gestured at Merula to sit back down by the cauldron while inspecting the milky substance. She measured it carefully both by volume and by weight, before pouring it into the potion while Merula stirred. It changed into a clear, light blue color with small specs of white swirling around in it. Penny picked out an empty bottle while Merula extinguished the flame. With the bottle filled with potion and a large toad returned to its natural habitat they agreed to meet up again at night when they could sneak down to the Black Lake and put their plan in motion. Merula however, had her own plans.

 

* * *

 

That night Merula only pretended to fall asleep behind the curtains of her four-poster bed. She could hear Ismelda snoring softly from the bed next to hers, and the other Slytherin girls were fast asleep. Liz was talking in her sleep as usual, mumbling something about a niffler stealing her glasses. The Slytherin dorms were quiet and peaceful.

Merula gazed at the canopy above her, tired but far from sleepy. She had thought about if she should bring Ismelda along with her tonight but had decided against it. She had to move quickly and without warning, so it was best to go solo. Besides, Merula was starting to suspect Ismelda might honestly be scared of water. When she was finally certain that the coast was clear, Merula carefully snuck out of bed and put her shoes on. She had gone to bed wearing a simple nightgown on top of which she put on a long black skirt and thick flannel shirt.

Wand in hand she carefully made her way out into the common room, where she had to tip-toe past a female prefect who had fallen asleep at one of the tables and was drooling on her parchment. Her cheek was covered in smudged ink and Merula almost felt bad for her, imagining how she would wake up with both her homework completely ruined and a whole night of work utterly wasted.

Barnaby was also there, just about to exit the common room and enter the corridor outside. Merula slapped her hands over her mouth to keep her giggles from waking up the prefect when she saw the bright green snake-shaped slippers on Barnaby’s feet. He glared at her and whispered angrily at her to stop laughing but the slippers were just so… so cute! It took a good ten seconds for her to get over the hilarious combination of big brawny boy and his tiny adorable slippers.

Barnaby looked displeased to say the least when she finally joined him, still grinning and shooting glances at his feet. The dungeons were usually not patrolled very carefully so sneaking through the underground hallways was easy enough, at least until you reached the lower floor with the main entrance. They avoided the main corridor and kept to the narrower passages and stayed as far away as they could from Snape’s office just in case.

It was dark and chilly but after four years living in the Slytherin common room they were well accustomed to it. The castle was very quiet at this hour, especially down beneath the surface floors. The only sounds came from their cautious feet and nervous breathing. Passing the kitchen Barnaby almost walked into a stack of barrels but Merula pulled him away at the last second. They rounded a corner and almost walked right into someone - in panic they both leapt back and prayed they had not been spotted but whoever it was came towards them. Heart pounding, Merula reached for her wand when someone peeked around the corner.

“Penny!” Barnaby sighed with great relief. “Thank goodness, I thought you were Professor Snape.”

“Oh! You surprised me too.” Penny said with a light laugh. Merula made a sour face and gestured at her to lower her voice.

“Oh SCHHH! Are you trying to get us caught?” Merula whispered angrily. “What are you doing in the dungeons?”

“Well...” Penny shot a quick glance at the stack of barrels. “Hufflepuff house is down here too, you know.”

“Oh.” Merula was grateful the darkness made sure nobody could see her cheeks turning pink. “I knew that, just… forgot for a second.”

“I didn’t know that.” Barnaby said with his usual confused expression.

The three of them continued up through the castle, carefully listening for any sign of patrolling teachers. Merula could feel her heart thumping in her chest and beads of sweat forming on her neck. At one point she swore she heard an angry hiss in the distance but she never saw Mrs Norris. She hoped sincerely some pet cat was just spooked by something and that it was not Mrs Norris catching one of their accomplices.

Finally they reached a narrow corridor leading them to a door that allowed them to exist out into the school grounds. Once outdoors, with the moon shyly peering through the clouds it was not very difficult to make it to the lake undetected. It was dark enough to cover them, but not so dark they were blind without light. The grass was wet with dew and Barnaby clearly regretted not changing into proper shoes before leaving. When wet his neon snakes looked sad and their necks bent as if in defeat.

The surface of the lake glittered softly as it moved, small waves shattering the surface. By the water, the shore was a pale silver grey where they waited for the others to come. Charlie came first, then M.C. arrived and told them the others would not join them tonight for various reasons but would help them deal with whatever they found tomorrow. Once gathered they had to move quickly however, there was no knowing when they might be spotted by a teacher, or worse yet the eternally bitter Mr Filch and his cat.

“Take one swig of the potion and then go into the water quickly. The effect is supposed to be almost immediate.” Penny whispered as they huddled together.

“What exactly is the effect anyway? I never read the parchment with all the potion stuff on it.” Barnaby whispered back.

“In the instructions it said that certain parts of our bodies will transform to let us move under water as if we were aquatic” Charlie explained. “I think we’ll probably become part fish or squid… or so I hope at least.”

“Oh so like merpeople?” Barnaby said with an excited look on his face.

“Yeah, or aquatic dragons!” Charlie replied, getting excited at the mention of his favorite fantastic beasts. Merula rolled her eyes and groaned.

“Whatever. The important part is it will work, right?”

Penny nodded and looked at M.C.

“Who do you think should go first? We haven’t tested it out yet…” She asked them. Merula intervened right away, it was time to make her move!

“I’ll drink it first, you dragged me along this far and now I want to take the lead!” She was determined and did not wait for M.C. to make any decision. Merula snatched the bottle from Pennys’ hands and chugged the lot of it right away.

Laughing at their dumbfounded faces, she ran to the water and got in with a splash. She could hear M.C. shouting something from the shore, but she could already feel her body changing and paid them no attention. First, her hands became longer and her fingers melted together to form strange fins. She felt as if a knife was ran across the sides of her neck but the pain was short lived and instead of open wounds she found a pair of scaled gills on each side, letting her stop holding her breath and taking in oxygen from the water instead. At first, it seemed her feet would take a similar form as her hands. However they would not stop at simply becoming longer and more paddle-like, her legs melted together same as her toes and grew longer. And thicker. Her socks ripped into pieces and her legs formed one big limb shaped like a fishtail, and her skin quickly turned from it’s usual soft texture into pale scales.

This was way beyond what she had expected, as she spun around in the water she felt like a brand new person. Her new fins felt awkward, but they were strong and made her turn swiftly in the water. Tightly gripping her wand Merula threw one last glance at the group on the shore and grinned when she swam down into the depths.


	2. Professors of Hogwarts

**Summary for the Chapter:**

> Merula has transformed herself into a mermaid but while doing so she has overdosed on a powerful magical potion, which is causing great concern among the people at Hogwarts. The efforts to save her begins with her rivals, and the professors of Hogwarts.

“That... That sly witch! She tricked us!” Barnaby yelled as Merula’s silhouette faded into the dark water. He picked up a rock off the shore and threw it into the water, but there was no sign of him hitting anything particular.

“Can’t say I’m surprised. Well, maybe a little surprised that she had the guts to drink that huge amount of potion that fast.” Penny said with a look of concern on her face.

“Calm down everyone, we have to decide what to do next.” Charlie put a hand on Barnaby’s shoulder to prevent him from launching more rocks at the innocent lake. M.C. rubbed their chin while considering the options.

“We could try to go after her somehow, or maybe go get more help? I bet Rowan would know everything there is to know about the lake…”

“It would take too long to run all the way back to the dorms and get Rowan without getting caught.” Penny said and looked across the lake, deep in thought. Her eyes fixed on something on the other side. Suddenly she gasped and covered her mouth with her hands, eyes wide in horror. “It’ll take too long! Merula drank so much it’s going to take too long for the effects to wear off!” Barnaby stared at Penny, head tilted to one side.

“What are you on about? Too long for what?” He asked her and Penny lowered her hands.

“You’re not supposed to drink more than a gulp or two, I read it on the back of the ingredient list. I didn’t really think it mattered since so many of us were going to share…” As what she was saying started to sink in, the group became even more baffled at the situation. Like professor Snape had lectured them about in potions class, overdosing on powerful potions was never a good idea.

“What will happen to her, Penny?” M.C. asked, choking a little as they spoke, and Penny shook her head, looking very much defeated.

“I still don’t quite get it but... Merula is in trouble, right?” Barnaby scratched his head and turned to M.C. “She kind of deserves it.”

“Still, we should go get help. She doesn’t deserve to spend the rest of her life in the Black Lake just because she stole a potion.” Charlie sighed deeply. Barnaby seemed impressed by Charlie’s level of empathy and gave him a swift slap on the shoulder.

“You’re a kind bloke, Weasley! Both with creatures and peoples!” He laughed. Charlie cracked a smile too but quickly turned to M.C, serious again.

“Come on, let’s go quickly. Who should we ask for help?”

“Professor McGonagall knows lots about transfigurations, but she’ll definitely punish the lot of us…” M.C. started but Charlie interrupted them.

“Plus I honestly hate the idea of disappointing her.”

“What about professor Snape? He could brew a cure…” Penny suggested but Barnaby shook his head right away.

“Let’s avoid professor Snape as long as we can. I’m already in trouble with him over a niffler I tried to keep in my dorm.” He said with a sour tone and the group went quiet. Remembering Sickleworth - the sweet and utterly destructive niffler that had accompanied M.C. for most of their entire fourth year, the group had a moment of silence. They all missed their only friend who all things said and done could rival Penny in charm.

“I suppose we can go to professor Flitwick.” M.C. suggested, breaking the quiet. “It’s been a while since we last disappointed him and he has always been helpful.”

Finally in agreement, the group set off back towards the castle to promptly ruin the evening for one of their favorite teachers.

 

* * *

 

“What on earth do you want at this hour? And what are you doing out of bed!” Wearing a striped blue pyjamas with a matching sleeping hat and big fluffy slippers, Professor Flitwick looked both surprised and angry when he opened the door to his office. Apologetic as they were, Flitwick would not let them say much until he finished scolding them. He took twenty points off each of their houses before letting them come in. They knew better than to complain about it so they just stared at their feet, Barnaby in particular seemed to feel remorseful about the situation.

The charms teacher’s office was dark and cold at this hour. The fireplace had but a few glowing embers left in it. Waving his wand, the professor lit large candles floating in the air and made chairs appear seemingly out of thin air. M.C. noticed an open door by the inner corner of the office, apparently leading to his bedroom. They could see an untidy bed with a strangely heavy looking cover on it in there. Still in his pyjamas and fluffy slippers Flitwick pointed his wand at the fireplace which instantly filled with blazing orange flames. He gestured at his students to sit in the conjured chairs.

“Now you will explain what on earth you’re here for in the middle of the night.” He spoke with a strict tone and gave them a piercing look. Penny was the first to come forward and speak.

“Professor, we’re very sorry about all this but we need help! Merula has been transfigured and might be stuck in the Black Lake!” The others nodded in agreement to back her up. “It’s partially our fault, but either way she needs our help and we don’t know what to do.” Penny’s voice broke off for a second, as if she was struggling to speak normally. “Please, help her professor.”

Understandably taken aback, professor Flitwick raised his voice yet again.

“Transfigured? Into what? And by what exactly?” When his students hesitated he gave them a look that resembled that of a parent demanding their child to speak the truth. M.C. was the first to buckle under the stare and lowered their head.

“Well, we made a syreni potion to explore the lake. Merula helped us with it and we were supposed to share it between all of us but… when we got to the lake she drank the entire bottle by herself. Penny believes she might not turn back if we don’t do something.” M.C. explained. They all looked timidly at Flitwick’s reaction, but to their relief he did not seem angry anymore.

“A syreni potion is no easy feat, nor is putting your classmate’s wellbeing before your own. If you had not been breaking the school rules and putting yourselves and miss Snyde in danger I’d call this quite impressive.” Flitwick adjusted his sleeping hat before continuing. “Now, we shall have to gather the other teachers and see how we can solve this matter.”

Professor Flitwick stood up, and with a smooth movement of his wand across his chest his pyjamas changed into his usual robes and then he walked out of his office, the four students following him in a row like ducklings after their mother.

A short while later they had worked up a sweat running between the teachers' living quarters and waking people up that might be able to help save the young Slytherin girl from becoming a permanent resident of the Black Lake. After going around the castle and explaining the situation to the discontent adults in the castle, professors Mcgonagall, Kettleburn and Snape, as well as Madam Pomfrey were gathered back in professor Flitwick’s office. Flitwick took a boiling kettle off the fireplace and poured tea for all of them.

M.C. and Charlie had lost yet another fifty points to their houses when they woke Snape up, but Penny and Barnaby had gotten off with just a disappointed scowl. The other teachers had showed greater mercy after they listened to Flitwick. Mcgonagall was the first to address the group of people. She too seemed deeply disappointed with them, especially Charlie who seemed to be struggling with avoiding her harsh glare.

“Miss Haywood, is it correct as M.C. said - that a syreni potion overdose is what has turned Merula into… well, a mermaid of sorts?” Penny nodded and Mcgonagall turned to Snape with a serious look on her face. He burrowed his brows and kept his gaze locked on the children.

“I can brew the girl a counter potion to reverse the transformation, however the bezoar needs to marinate for at least three days to get the desired effect in this particular case. Otherwise, it will be too weak to reverse the damage miss Snyde has done to herself” He said slowly. Madam Pomfrey scoffed.

“What do we do with the girl until it’s finished? Leave her in the Black Lake with all the horrors in there? I will not have a near dead child come up to my hospital wing in three days unless it is absolutely unavoidable!” Pomfrey had a fiery look of determination and protective concern on her face.

“We can take shifts bringing her food and keeping her company. Professor spout has informed me she has plenty of fresh gillyweed ready for harvest.” Professor Flitwick chipped in.

“An excellent idèa!” Kettleburn grinned widely. “Is there enough to go around for the students as well perhaps? I could take this opportunity to teach her and the other fourth years all about the lake’s creatures up close and personal. I never thought I’d have this great an opportunity for an underwater lesson…” He went silent when he saw the look Madam Pomfrey gave him.

They discussed the matter thoroughly until they ran out of tea and dispersed. Snape went straight to the dungeons to start his counter potion, Mcgonagall went to send word to Dumbledore. Madam Pomfrey and Flitwick headed down towards the lake with M.C. and their friends right behind them. Madam Pomfrey insisted that Merula must receive a check up as soon as possible and had asked Kettleburn to go tend to her patients in the hospital wing. The man had a lot of experience with healing magic after all the physical trauma inflicted on him by various fantastic beasts.

The lake was calm and quiet when they approached it. Not even the giant squid was anywhere to be seen, and there was no sign of Merula. M.C. glanced at professor Flitwick and wondered how much they should tell him about the vault in the lake. Would it help get Merula back to safety if they shared their information? Deep, anxious concern started filling their gut rapidly. It would put them and their friends into much deeper trouble, but even so it was more important to save Merula… was it not? Could Merula really die down there if they failed to help her? Their thoughts begun to race but suddenly, Penny nudged them with their elbow gently, breaking their string of worried thoughts.

“Hey, don’t worry. We’ll get her back.” She whispered softly, and gave M.C. a big, bright smile. The confidence in her smile was contagious, and the anxious feelings gave way for a warm appreciation of Penny. M.C. could feel their own lips curl upwards as they met Penny’s eyes.

“Thanks. We’ll be okay, I know we all will.”

When they reached the shore, professor Flitwick turned to them and looked sternly at Barnaby.

“Mister Lee, run down and fetch Hagrid from his Hut. Tell him we need to use the boats, two of them to go out and search the lake.” Barnaby exchanged a look with M.C. and the others, but obediently ran down the grassy path towards the groundskeeper’s hut where the windows were still lit and dark smoke rose from the chimney.

“Professor, will we be searching the lake with you?” Charlie asked.

“No, you will not be going under the surface under any circumstances. I simply wish to keep you as included as possible to give you a chance to learn from this before your punishments.” Flitwick replied. His glasses gave his eyes a glossy shine to them, obscuring what exactly might be going through his head at that moment.

Once Hagrid had arrived and two of the boats traditionally carrying the first year students across the lake on their very first night at Hogwarts were in the water they split into two groups to go on board. Professor Kettleburn helped Madam Pomfrey into the other one and M.C. and Barnaby followed them, then Charlie, Penny and professor Flitwick jumped into Hagrid’s boat. Hagrid took the lead with swift, powerful strokes of his oars while Barnaby and Kettleburn took one oar each. The surface broke under them and the waves splashed against the sides of the rowboats. M.C. peered into the water and understood why the lake had earned its name - when you looked into the depths it was as if looking into darkness itself. Nearest the surface there was a green tone to the water, and the surface itself shimmered beautifully as all water does. However, you did not need to get far from the beach before the lake became very deep and indeed, very black.

Their mouth was dry but M.C. still felt a need to swallow, and redirected their focus to the people on board the boat. Madam Pomfrey was fixated on the water, but her face glowed with determined concern rather than fear. Kettleburn on the other hand seemed cheerful, whistling as he rowed. Barnaby did not seem too worried either, his eyes followed the tip of his oar as he rowed steadily and kept up with Kettleburn’s pace. It struck M.C. how physically fit Barnaby was, and felt something stir slightly in the bottom of their gut, although they could not quite identify the feeling.

Flitwick stood up in the rear of his boat, and brought his wand out. Raising it far above his head, he shouted “ _vermillious!_ ” and bright red sparks shot out of his wand into the sky above the lake. With all of them observing closely, he then lowered his wand and instead pointed it directly at the lake. He cleared his throat again.

“ _Vermillious maxima!_ ” Bright, sparkling red light shot down into the water, lighting a path down into the depths. The water looked almost like blood where the rescue signal lit it up.

Copying their teacher, Penny, Charlie and M.C. shot their own sparks down into the water and the sky. Hoping that Merula would see the bright sparks and understand that help was up here, they went around the lake for about an hour.

M.C. wondered if Merula might not be more turned off than tempted by the bright red light, but they trusted Flitwick and the other adults to know what to do. The air was cold and the wind was harsh out on the water. Once they had rowed a few laps around the water they went back to the shore where M.C. and the other students got dropped off. Hagrid went back out on the lake with Flitwick, while Madam Pomfrey led the students back towards the castle. The entire way back the school healer lectured them on the importance of safety first and never to experiment with illegal potion-making.

“All potions are poisons when used or made incorrectly!” She said meaningfully as they passed through the castle doors. Penny exchanged a look of amusement with M.C. and the two had to try hard not to giggle too loud on their way back towards the common rooms.

Meanwhile, Merula was going further and further down into the heavy darkness of the Black Lake. 


	3. The Black Lake

**Summary for the Chapter:**

> Merula's venture into the Black Lake continues and she experiences a darkness unlike anything before. A new friend might not be enough to prevent the inevitable lonliness that awaits her on her quest to find the vault.

The Black Lake truly earned its name. Merula could hardly see a thing except for the pale, shimmering surface above her and dark shadows of seaweed scattered across the lake bottom. Everything was terribly blurry. Sediment flurried up off the ground when her strong tail stirred the water and muddied the water around her. She had to make sure she stuck close to the bottom, fearing she could be followed if they saw her at the surface and that it would be too difficult to orient in the middle of the water. She checked how far below the muddy floor was every few minutes to make sure she was at the right depth and moving towards the lake’s center. Once she figured she was deep enough to not be spotted from the shore she paused and raised her wand above her head.

“ _ Lumos maxima!” _ Her voice had a strange, unsettling tone to it as if it no longer belonged to a human, but she still had her magic and the wand lit up and spread a bright white light around her. In the sudden light her eyes caught a small group of silvery fish swimming away from her.  The water was very filthy, particles of mud from the lake bottom floating all around. There were also other junk surrounding Merula, leaves and rotten sticks covered the ground and some of it stirred into the water as she flicked her fins. A lonely, empty chocolate frog box half-floated meekly just below her, the cardboard partially decomposed and coloring faded. Merula recalled what she could about the lake from her history of magic classes. Despite professor Binn’s very boring way of teaching she had picked up quite a few facts about the school itself, by far the most interesting magical history topic. The lake was even older and larger than the castle, with a unique ecosystem and some unique species she would have to be vary of. Of course there was also the giant squid. Professor Kettleburn insisted they could and should befriend their supposedly gentle giant but Merula was not entirely enticed by the thought of getting within tentacle-range of anything that large. Sometimes she would watch it swim around outside the Slytherin common room windows, but that was plenty close enough contact with the beast in Merula’s opinion. 

_ Perhaps a hug and treat could convince it to show me around though.  _ Merula thought with a bubbling snort.  _ Too bad I have no treats. _

She figured she would have to work quickly before the potion wore off. She recalled Penny talking about how what they were searching for is at the very middle of the lake. With this goal in mind she put more strength into her swimming and zoomed rapidly through the water.

While she was passing above a large patch of long seaweed she felt something try and grab at her tail. A grindylow that had been hiding there had jumped up. It snarled at her when she looked at it, and another one put it’s claws around her arm the second she slowed down. Merula yelped loudly and spun around, poking the beast holding her arm in the eye with her wand. The creature screamed and now several grindylows were coming out of the seaweed to try and drag her down. With no time to feel afraid, Merula furiously smacked one of them with her tail. The large fin hit it right in the face and it went twirling unconscious back down towards the ground and disappeared. Strangely empowered, seeing just how strong her new limb was, she threw herself at the grindylows, fury coursing through her veins. She struck another one, hitting this one in the gut and sending it back down. There were so many of them now, a dozen of them coming out of the seaweed below. Attempting to propel herself away from them she pushed back hard with her tail but they were behind her now, too.

Sharp fingers had grabbed her by the hair, scratched her back and ripped through her flanell. The furious confidence that had filled her a minute ago seemed to drain out of her like water from a toilet, flushing. Her stomach felt as if it was spiraling into a tense knot of fear and she lost her focus - her mind going completely blank in the moment where she most needed her thoughts. She tried hard to think, to think of anything at all that might get her free. Flailing with her arms and tail she could not do anything to get rid of the terrible creatures tearing at her.

She felt herself sink now. The grindylows were pulling her down, dragging her by her hair and arms. Her wand was still clutched in her hand, still lit by the lumos charm. Merula did not know if it was her imagination but it felt as if the handle was warm and vibrating against her palm. It almost felt like it  _ wanted  _ something, like it was trying to tell her to act... Merula struggled enough to point it at one of the grindylows pulling at her arm.

“ _ Stu-”  _

A bright golden flash interrupted her before she could stun the snarling grindylow holding on to her right arm. The grindylow fell away with a whining noise, and another shiny flash struck a second blow to another one. 

It was one of the merpeople, Merula suddenly remembered hearing about them from professor Kettleburn. A tall creature of human-like intelligence with a long fish-like tail that lived in the lake. To Merula they looked very much like how she had imagined mermaids. It was fighting the evil beasts with a golden spear, shaped like a trident. It was long, sharp and a very impressive weapon he wielded. The long golden shaft between the deadly forked tips was wrapped in cloth and had plenty of room for him to grasp it as he pleased and quickly change the positions of his hands to strike however he pleased. The Just as Merula realized it was trying to save her, the merman stabbed one of her attackers in the gut, spearing it. Blood flowed everywhere now, and the rest of the grindylows screeched as they fled from him. 

Finally able to break free, Merula swam as quickly as she could up and away from the seaweed below. It was only now she took in how much her arm was bleeding, sharp pain pulsated where the grindylow had left a deep cut in her flesh and the blood left a trail behind her. In an attempt to control it somewhat she put her hand over the wound and tried to press the flesh back together. It hurt something terrible and it took all her strength not to cry out.

The merman swept up in front of her now, holding his trident in an angle towards her. His face had a sharp, almost mean look to it. His large green eyes had pupils like a lizard, his long hair was almost reminiscent of weeds and his muscular body was covered in tight gray skin. Despite just saving her life, he seemed not quite convinced she was not an enemy herself.

“Who are you?” He asked calmly. Merula considered if she should lie, and how he might react depending on her answer. 

“My name is Merula.” Hearing it out loud in this scenario she realized how much her name actually sounded like it may as well be the name of a mermaid, and for some inexplicable reason this boosted her confidence. 

“Merula. Why is it you look almost like one of our peoples, and yet you carry a wand like the surface wizards?” He spun his trident in his hand, looking her up and down as he spoke. 

“I- I’m looking for something.” Merula blurted out. The merman narrowed his eyes at her.

“You do not answer?” He hissed and Merula knew it was a bad move to try and distract him. 

“S-sorry. I am a witch, from the surface. I’m a student at the school.” 

_ Might as well tell the truth at this point.  _ She hugged her injured arm tighter with her hand. The knot in her stomach tightened again now, but at least she was not panicking anymore. When the merman did not speak she cleared her throat and continued.

“Thank you for saving me, I-, I was transformed and I need to find something down here before I can return to the surface.” 

“We do not welcome surface peoples here.” He was still eyeing her. “You say you were transformed? I did not know magic could do this... Your appearance is… very familiar.” 

“Oh, yeah. We made a potion. Got to admit I really admire the strength of this tail - much better than legs.” Merula giggled nervously. To her surprise the merman started laughing too.  He lowered his trident and came close to her, she made sure to aim her wand away from him, too. 

“Very well, Merula. What do you seek?” 

“It’s a place, actually. We call it a cursed vault - should be in the very center of the lake. Probably someplace hidden away.”

“A curse? Why would you look for a curse?” The merman was quite close now, circling her slowly. Merula told herself he was not doing it to scare her… probably.

“I want to break it.” She said, louder than intended. At least she sounded very confident. The merman nodded slowly and stopped circling around her. 

“Come, there is a possibility I know this place. It is not far.” He swam off, and Merula did her best to keep up with him. 

“Wait, what’s your name?” Merula asked him as she swam after him, only now realizing she had completely forgotten to ask.

“Pike” he answered with a bemused look at her. He then looked at her injured arm and the blood leaking through her fingers. He tore at the fabric wrapped around the shaft of his golden trident and unwrapped it, then swam close to Merula and offered it to her. 

“You are injured, use this and stop the bleeding.” 

The cloth looked dirty. It had a greyish brown color to it and small specks of green in between the threads. Merula hesitated to accept it, as much as she wanted a bandage it simply did not look hygienic. Then again she knew nothing of merpeople courtesy and if it would be considered very rude to refuse such a helpful gift from the person who just saved her life. Pike seemed to notice her hesitation, and Merula realized she must look quite rude in that moment.

“Oh, thank you.” She said, wanting to kick herself in the groin when she heard how ungrateful her tone sounded. Pike furrowed his brow slightly.

“It is a good healing cloth. Enhanced with the best medical herbs of my people. That is why I carry it on my weapon - to use if I must fight and get injured.”

“Oh right. That makes a lot of sense actually.” Less hesitant now, Merula wrapped the cloth tightly around her arm to cover the cut. “Thank you, Pike.”  

Suddenly Merula’s blood was not the only red they saw - above her the water lit up in bright red. At first it scared her worse than the grindylows had and the merman shouted in surprise. The light became more intense the more she looked at it. It felt somehow familiar, although she could not quite decide where she had seen it before. It looked like it had been conjured with magic at least - could it be M.C. and their group attempting to get at her from above the surface? She was not sure, but she was sure she was not going up there without taking full 

advantage of the effects of the syreni potion first.

Pike seemed even more unsettled by the red light than she was. 

“That… do you know what it is? Is it dangerous?” He asked her with a significant note of anger in his voice. 

“No, but it does look like it’s magic.” She said honestly. Pike muttered something foul under his breath but Merula was not interested in which exact words he used to express his disdain for the magic red light above. They continued forward far more carefully, Merula clutched her wand tightly and kept looking up. She was hoping to see what might be the source of the lights, but she was so far below whatever it was she could not.

The merman Pike brought her past what Merula thought looked just like an underwater village. She tried to ask him if that was his home but he told her to be quiet and not wake up the other merpeople. When they had put some distance between themselves and the village he spoke again and explained he had been on patrol when he heard her shouting and had left his route thinking it was one of the teenagers of his people that had snuck out and gotten into trouble. From the sound of it, underage merpeople had a curfew just like the students did at Hogwarts - and just as strong a tendency to break it.

It became noticeably darker now, and significantly colder. They approached a ravine and hovered over the edge of it. Below them was a steep increase in depth leading almost straight down into cold, crushing darkness. Pike put his hand on Merula’s shoulder.

“This is the place. We have never gone down there, not further than a few paces. But I can accompany you if you want me to.” Pike gazed into Merula’s eyes with a deep and serious look.

“Why… why do you want to help me this much?” Merula asked sincerely. She genuinely wondered why Pike would even offer to tag along when it was clearly scary and dangerous. He had already helped her so much and if he was supposed to be patrolling like he had claimed did he not have to get back to his duty? It did not make sense to her why he would not just have gone back home by now, and Pike seemed flustered by her question. He let go of her shoulder and touched the back of his neck instead, rubbing it as he spoke.

“I’m enjoying myself I guess.” He cleared his throat when she saw how Merula glared at him and clarified. “Well, this is honestly quite fun. I haven’t had the experience of swimming around at night with a beautiful girl… I admit it’s exciting.”

This was just about the last thing Merula had expected to come out of the merman’s mouth. Of course a late night illegal venture into a large unexplored lake full of magical creatures was bound to contain much excitement and shocking adventure, but the sort of surprises she had expected involved a lot more lethal danger to her person than… being called beautiful by a half-fish-half-man person. She did not know how to process the words coming out of him and tried hard not to let her own mouth fall open in confused bewilderment. 

“Ohhh. Uhhh. Wow… yes.” It was if her tongue had suddenly become unbearably clumsy and she stumbled over the words she tried to pronounce. “Thank you then.” 

She wanted to slap herself in the face. Cursing internally and unable to look Pike in the eyes she scratched her head to distract herself.  _ Really, Merula?! What are you saying!! _

Pike too seemed embarrassed now, but he remained calm as far as Merula could tell. In silence they swam down the ravine. Merula’s wand shone brightly in the near total darkness. She felt the pressure on her increase now, and thought of how deep she must be under water. She tried not to think about how far away the surface must be by now and wonder what she would do if the syreni potion wore off while she was down here.

It was growing colder and colder. The water around her was becoming too cold even for her mermaid skin, which had kept her fairly comfortable up until now. She turned around to check in with Pike, but he was not there. 

“Pike?” 

She turned around again, looking around every side of her. 

“Pike!” 

Her voice echoed against the ravine walls and it was the only response she got. Pike was gone, and Merula had not even noticed him disappearing. The cold of the water seemed to seep through her skin, her flesh, all the way into her spine. She had never felt so alone.


	4. The Cursed Vault

**Summary for the Chapter:**

> The mystery escalates as Merula reaches the bottom, facing the challenges at the very bottom of the Black Lake. She will be rewarded for her efforts, but with it comes a warning of what has yet to come for the young witch.

The deep ravine was pitch black. Merula could not see anything, it was as if she had lost her eyesight completely. The water pressure was soon so great it seemed to be forcing her deeper into the ravine, all the while making it more difficult to breathe and move than before. Cold seemed to radiate from the bottom, chilling her to her very core, and yet she had to keep pressing forward. Claustrophobia built up inside her but she forced herself to remain in control of her thoughts and her goal, clinging onto the grip of her wand as if it was her only chance at survival. She had an overwhelming gut feeling that there was no possibility of her making it out of this situation if she did not enter the vault and break its curse.

With no allies, no friends, not one person there next to her she had to fully rely on her own resourcefulness. Determined to believe in herself, she pushed on as hard as she could.

After what felt like half an eternity, a flickering light finally appeared. Wanting to scream in relief she swam as fast as she could towards it and as she came closer she saw it was a small, grey flame, suspended over a pillar, carved out of some sort of black stone. The grey light illuminated the lake floor around the pillar, where small shelled creatures crawled around in the sand. She noticed an old scarf lying next to the pillar, it looked like one of the striped Hogwarts scarves but the colors were too faded to make out in the grey light from the mysterious flame. She picked it up and the embroidered crest stitched on read “GRYFFINDOR” underneath a posing lion.

_What is a Gryffindor scarf doing down here? Did it belong to a student that’s gone down here before?_ Merula wondered to herself. Not wanting to waste a potential clue, she tied it around her waist.

Examining the black pillar carefully in the light from the brightest _lumos_ charm she could conjure, she found a perfectly round slot someone must have carved into the stone. Suspecting something was supposed to be inserted into this slot, she had another look around the area. It took several minutes of swimming around the pillar, hovering her lit wand over the lake floor and poking at the shelled creatures to get them to move so she could see if there was anything to be found in the sand. One of them was particularly stubborn and did not want to move from the small rock it was sitting on top of. Even after several gentle pokes it refused to let go of it’s grip until Merula impatiently smacked it with her hand.

The stone the creature had been sitting on was perfectly round, and looked just the size of the slot too. Triumphant Merula snatched it from the floor but as soon as she touched it it cracked in her hand. Two perfect halves with a smooth crack in the middle, it looked as if it had been cut with a knife.

Pointing her wand at the stone, she said “ _reparo,_ ” in an attempt to make the two halves reunite, but the stone remained split. She swam over to the pillar, and figuring she just might as well she shoved the pieces into the slot so they filled the round hole.

The pieces went in, and sparks emerged from the crack between them. Amazed, Merula stared at it as the stone pieces melted into a whole again, sending bright and beautiful sparks out of the slot. When the stone was whole again it shone, the surface was smooth and shiny unlike before. A moment later loud cracking noises emerged from the pillar, and from underneath her.

The pillar began to rise from the sand, seemingly spiraling upwards, all the while shaking the ground underneath Merula. The shelled creatures all seemed to go into a frenzy and ran as quick as their little legs would carry them away from the pillar. As the pillar rose up it became wider and wider, finally revealing an opening like that of a doorway, leading into somewhere pitch black and from what Merula could tell - very, very cold. She caught glimpses of ice glittering behind the doorway and when the pillar stopped rising a wave of tiny ice flakes fell out of it. The grey fire flickered above, shining even less light around her now.

Wand raised in front of her, Merula slowly approached the dark space inside the pillar.

The inside of the pillar must have been magically enlarged as it was far larger than seemed possible from the outside. It was a round room with a large object in the middle that emitted a warm, orange glow. The walls and the floor of the room was covered in ice and remembering the first time she had attempted to enter a cursed vault Merula was grateful to being able to hover in the water and not have to put her feet against the freezing floor. Shivering, she reached out towards the glowing object.

_The vault._ Merula thought. _This must be the vault! I made it!_

Her hand was shaking when she touched it. Somehow, the surface felt hot despite the cold of the room. She nearly jerked her hand back from the shock of it, the contrasting temperatures felt deeply unpleasant, but she held her palm pressed firmly against it and slowly it seemed to spread its inner warmth throughout her body. Heat streamed up her arm and into her chest, and with it an profound feeling of reassurance that filled her head with old memories. She suddenly remembered the feeling of her mother’s arms around her, the beating sound she heard from her father’s heart when she pressed her head against his chest, precious moments from her childhood before they were ripped away from her.

The vault began to open and as it did the ice all around the room melted, the temperature of the water rising rapidly and becoming far more pleasant. As the inside of the vault revealed itself, a large egg and a golden key appeared. The egg stood out the most, it looked as if it had been made entirely out of melted marble with all the colors of the rainbow. Mesmerized, Merula stared at the items and wondered if this is how it had been for M.C. every time they opened a cursed vault since they started Hogwarts. A deep shiver ran down her spine and she heard someone speak to her from inside the vault.

_There is more to be discovered, but further than this no witch can go alone… you must choose company if you wish to take the right path._

As the voice disappeared, the silence was deafening. Merula would have grown terrified now had it not been for the warmth from the vault lingering inside her. Snapping back to her senses, she picked up the egg and the key and shoved them both into the Gryffindor scarf, wrapping it into a makeshift wrap for the items. With this tightly clenched in her hand she swam out into the open and dashed upwards. She could hear the black pillar cracking again, and without looking back she knew it must be closing again behind her.

The water in the ravine was nowhere near as cold nor as dark as before, and she had to press on with all her strength to force her body up against the pressure. She had no intention of stopping but when she breached the edge of the cliff where she and Pike had gone down, she heard him yelling out at her and she stopped her ascent abruptly.

Pike was coming towards her, but he was not alone now. Several grown merpeople swam behind him, spears and tridents held high in their scaled hands.   

“Merula!!” Pike shouted at her, “What happened? I do not understand I- I tried to follow but before I knew it I was back here and even as I went down again I just got brought back here!”

“You didn’t hear me shouting for you?” Merula asked him, trying her best to sound calm.

“No, I’m… I’m so sorry…” Pike looked deeply ashamed to Merula’s astonishment. They had only known each other for less than a night and they were not even of the same species.

“It’s not like you owe me anything, I mean we just met and-” Merula suddenly realized the other merpeople had surrounded her while she was speaking to Pike. They did not look friendly either.

“Uh, what’s going on?” Merula asked them, and hurried to _nox_ the light out of her wand.

“I’m sorry Merula. I had to go to my people when I could not follow you.” Pike’s voice was cracking as he spoke, but he rose his own trident just like the merpeople surrounding her. “Did you break the curse?”

“Yes.” Merula replied without hesitation. “I opened the vault and I broke the curse on it. You can feel how the ravine is far less dangerous now.”

The merpeople exchanged looks but they did nothing to back down. Thinking rapidly, Merula ransacked her brain for a way to get as far away from them as she possibly could.

“Then we thank you, but you must give us the egg you found inside.”

Merula wrinkled her forehead, “how do you know I found an egg?”.

A mermaid behind her hissed.

“An egg was stolen from us by a human as the curse appeared! That egg is an innocent!” This mermaid seemed the most hostile, jerking her weapon back and forth as if she could just barely stop herself from spearing Merula like a fish kebab. As inclined as she was to appease the clearly threatening mermaid, Merula did not want to part with what she had found in the vault. Not after all the effort she had gone through to open it. She was not so morally corrupt she would knowingly snatch a baby from its family, however something about this situation did not quite add up.

“Are you sure this is your egg? What do merpeople eggs even look like?” Her question was not well-received. All but Pike hissed loudly at her this time, but she decided to stand her ground. “If you can describe it to me and it’s the same as what I found then it is yours, I swear it.”

“Our eggs are round and light grey, with red and green streaks. You can hear the little ones humming from within.” Pike finally answered her after a tense silence. Merula opened up the scarf and brought out the egg, taking in the looks of painful disappointment on the faces of the merpeople. The mermaid who had spoken earlier seemed the most affected, her eyes twitching.

“Go then, but do not come back here. You may have broken the curse, but opening the vault has opened our wounds anew.” Pike said, and when Merula looked into his eyes she knew it was for the better if it was the last time.

Merula nodded, wrapped the egg back into the scarf, and swam alone towards the surface far above.


End file.
